Added trace operation + test and renamed base2k to backend

backend/src/vec_znx.rs

@@ -0,0 +1,373 @@
+use itertools::izip;
+
+use crate::DataView;
+use crate::DataViewMut;
+use crate::ScalarZnx;
+use crate::Scratch;
+use crate::ZnxSliceSize;
+use crate::ZnxZero;
+use crate::alloc_aligned;
+use crate::assert_alignement;
+use crate::cast_mut;
+use crate::ffi::znx;
+use crate::znx_base::{ZnxInfos, ZnxView, ZnxViewMut};
+use std::{cmp::min, fmt};
+
+/// [VecZnx] represents collection of contiguously stacked vector of small norm polynomials of
+/// Zn\[X\] with [i64] coefficients.
+/// A [VecZnx] is composed of multiple Zn\[X\] polynomials stored in a single contiguous array
+/// in the memory.
+///
+/// # Example
+///
+/// Given 3 polynomials (a, b, c) of Zn\[X\], each with 4 columns, then the memory
+/// layout is: `[a0, b0, c0, a1, b1, c1, a2, b2, c2, a3, b3, c3]`, where ai, bi, ci
+/// are small polynomials of Zn\[X\].
+pub struct VecZnx<D> {
+    pub data: D,
+    pub n: usize,
+    pub cols: usize,
+    pub size: usize,
+}
+
+impl<D> ZnxInfos for VecZnx<D> {
+    fn cols(&self) -> usize {
+        self.cols
+    }
+
+    fn rows(&self) -> usize {
+        1
+    }
+
+    fn n(&self) -> usize {
+        self.n
+    }
+
+    fn size(&self) -> usize {
+        self.size
+    }
+}
+
+impl<D> ZnxSliceSize for VecZnx<D> {
+    fn sl(&self) -> usize {
+        self.n() * self.cols()
+    }
+}
+
+impl<D> DataView for VecZnx<D> {
+    type D = D;
+    fn data(&self) -> &Self::D {
+        &self.data
+    }
+}
+
+impl<D> DataViewMut for VecZnx<D> {
+    fn data_mut(&mut self) -> &mut Self::D {
+        &mut self.data
+    }
+}
+
+impl<D: AsRef<[u8]>> ZnxView for VecZnx<D> {
+    type Scalar = i64;
+}
+
+impl<D: AsRef<[u8]>> VecZnx<D> {
+    pub fn rsh_scratch_space(n: usize) -> usize {
+        n * std::mem::size_of::<i64>()
+    }
+}
+
+impl<D: AsMut<[u8]> + AsRef<[u8]>> VecZnx<D> {
+    /// Truncates the precision of the [VecZnx] by k bits.
+    ///
+    /// # Arguments
+    ///
+    /// * `basek`: the base two logarithm of the coefficients decomposition.
+    /// * `k`: the number of bits of precision to drop.
+    pub fn trunc_pow2(&mut self, basek: usize, k: usize, col: usize) {
+        if k == 0 {
+            return;
+        }
+
+        self.size -= k / basek;
+
+        let k_rem: usize = k % basek;
+
+        if k_rem != 0 {
+            let mask: i64 = ((1 << (basek - k_rem - 1)) - 1) << k_rem;
+            self.at_mut(col, self.size() - 1)
+                .iter_mut()
+                .for_each(|x: &mut i64| *x &= mask)
+        }
+    }
+
+    pub fn rsh(&mut self, basek: usize, k: usize, scratch: &mut Scratch) {
+        let n: usize = self.n();
+        let cols: usize = self.cols();
+        let size: usize = self.size();
+        let steps: usize = k / basek;
+
+        self.raw_mut().rotate_right(n * steps * cols);
+        (0..cols).for_each(|i| {
+            (0..steps).for_each(|j| {
+                self.zero_at(i, j);
+            })
+        });
+
+        let k_rem: usize = k % basek;
+
+        if k_rem != 0 {
+            let (carry, _) = scratch.tmp_slice::<i64>(n);
+            let shift = i64::BITS as usize - k_rem;
+            (0..cols).for_each(|i| {
+                carry.fill(0);
+                (steps..size).for_each(|j| {
+                    izip!(carry.iter_mut(), self.at_mut(i, j).iter_mut()).for_each(|(ci, xi)| {
+                        *xi += *ci << basek;
+                        *ci = (*xi << shift) >> shift;
+                        *xi = (*xi - *ci) >> k_rem;
+                    });
+                });
+            })
+        }
+    }
+}
+
+impl<D: From<Vec<u8>>> VecZnx<D> {
+    pub(crate) fn bytes_of<Scalar: Sized>(n: usize, cols: usize, size: usize) -> usize {
+        n * cols * size * size_of::<Scalar>()
+    }
+
+    pub(crate) fn new<Scalar: Sized>(n: usize, cols: usize, size: usize) -> Self {
+        let data = alloc_aligned::<u8>(Self::bytes_of::<Scalar>(n, cols, size));
+        Self {
+            data: data.into(),
+            n,
+            cols,
+            size,
+        }
+    }
+
+    pub(crate) fn new_from_bytes<Scalar: Sized>(n: usize, cols: usize, size: usize, bytes: impl Into<Vec<u8>>) -> Self {
+        let data: Vec<u8> = bytes.into();
+        assert!(data.len() == Self::bytes_of::<Scalar>(n, cols, size));
+        Self {
+            data: data.into(),
+            n,
+            cols,
+            size,
+        }
+    }
+}
+
+impl<D> VecZnx<D> {
+    pub(crate) fn from_data(data: D, n: usize, cols: usize, size: usize) -> Self {
+        Self {
+            data,
+            n,
+            cols,
+            size,
+        }
+    }
+
+    pub fn to_scalar_znx(self) -> ScalarZnx<D> {
+        debug_assert_eq!(
+            self.size, 1,
+            "cannot convert VecZnx to ScalarZnx if cols: {} != 1",
+            self.cols
+        );
+        ScalarZnx {
+            data: self.data,
+            n: self.n,
+            cols: self.cols,
+        }
+    }
+}
+
+/// Copies the coefficients of `a` on the receiver.
+/// Copy is done with the minimum size matching both backing arrays.
+/// Panics if the cols do not match.
+pub fn copy_vec_znx_from<DataMut, Data>(b: &mut VecZnx<DataMut>, a: &VecZnx<Data>)
+where
+    DataMut: AsMut<[u8]> + AsRef<[u8]>,
+    Data: AsRef<[u8]>,
+{
+    assert_eq!(b.cols(), a.cols());
+    let data_a: &[i64] = a.raw();
+    let data_b: &mut [i64] = b.raw_mut();
+    let size = min(data_b.len(), data_a.len());
+    data_b[..size].copy_from_slice(&data_a[..size])
+}
+
+#[allow(dead_code)]
+fn normalize_tmp_bytes(n: usize) -> usize {
+    n * std::mem::size_of::<i64>()
+}
+
+#[allow(dead_code)]
+fn normalize<D: AsMut<[u8]> + AsRef<[u8]>>(basek: usize, a: &mut VecZnx<D>, a_col: usize, tmp_bytes: &mut [u8]) {
+    let n: usize = a.n();
+
+    debug_assert!(
+        tmp_bytes.len() >= normalize_tmp_bytes(n),
+        "invalid tmp_bytes: tmp_bytes.len()={} < normalize_tmp_bytes({})",
+        tmp_bytes.len(),
+        n,
+    );
+
+    #[cfg(debug_assertions)]
+    {
+        assert_alignement(tmp_bytes.as_ptr())
+    }
+
+    let carry_i64: &mut [i64] = cast_mut(tmp_bytes);
+
+    unsafe {
+        znx::znx_zero_i64_ref(n as u64, carry_i64.as_mut_ptr());
+        (0..a.size()).rev().for_each(|i| {
+            znx::znx_normalize(
+                n as u64,
+                basek as u64,
+                a.at_mut_ptr(a_col, i),
+                carry_i64.as_mut_ptr(),
+                a.at_mut_ptr(a_col, i),
+                carry_i64.as_mut_ptr(),
+            )
+        });
+    }
+}
+
+impl<D> VecZnx<D>
+where
+    VecZnx<D>: VecZnxToMut + ZnxInfos,
+{
+    /// Extracts the a_col-th column of 'a' and stores it on the self_col-th column [Self].
+    pub fn extract_column<R>(&mut self, self_col: usize, a: &R, a_col: usize)
+    where
+        R: VecZnxToRef + ZnxInfos,
+    {
+        #[cfg(debug_assertions)]
+        {
+            assert!(self_col < self.cols());
+            assert!(a_col < a.cols());
+        }
+
+        let min_size: usize = self.size.min(a.size());
+        let max_size: usize = self.size;
+
+        let mut self_mut: VecZnx<&mut [u8]> = self.to_mut();
+        let a_ref: VecZnx<&[u8]> = a.to_ref();
+
+        (0..min_size).for_each(|i: usize| {
+            self_mut
+                .at_mut(self_col, i)
+                .copy_from_slice(a_ref.at(a_col, i));
+        });
+
+        (min_size..max_size).for_each(|i| {
+            self_mut.zero_at(self_col, i);
+        });
+    }
+}
+
+impl<D: AsRef<[u8]>> fmt::Display for VecZnx<D> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        writeln!(
+            f,
+            "VecZnx(n={}, cols={}, size={})",
+            self.n, self.cols, self.size
+        )?;
+
+        for col in 0..self.cols {
+            writeln!(f, "Column {}:", col)?;
+            for size in 0..self.size {
+                let coeffs = self.at(col, size);
+                write!(f, "  Size {}: [", size)?;
+
+                let max_show = 100;
+                let show_count = coeffs.len().min(max_show);
+
+                for (i, &coeff) in coeffs.iter().take(show_count).enumerate() {
+                    if i > 0 {
+                        write!(f, ", ")?;
+                    }
+                    write!(f, "{}", coeff)?;
+                }
+
+                if coeffs.len() > max_show {
+                    write!(f, ", ... ({} more)", coeffs.len() - max_show)?;
+                }
+
+                writeln!(f, "]")?;
+            }
+        }
+        Ok(())
+    }
+}
+
+pub type VecZnxOwned = VecZnx<Vec<u8>>;
+pub type VecZnxMut<'a> = VecZnx<&'a mut [u8]>;
+pub type VecZnxRef<'a> = VecZnx<&'a [u8]>;
+
+pub trait VecZnxToRef {
+    fn to_ref(&self) -> VecZnx<&[u8]>;
+}
+
+pub trait VecZnxToMut {
+    fn to_mut(&mut self) -> VecZnx<&mut [u8]>;
+}
+
+impl VecZnxToMut for VecZnx<Vec<u8>> {
+    fn to_mut(&mut self) -> VecZnx<&mut [u8]> {
+        VecZnx {
+            data: self.data.as_mut_slice(),
+            n: self.n,
+            cols: self.cols,
+            size: self.size,
+        }
+    }
+}
+
+impl VecZnxToRef for VecZnx<Vec<u8>> {
+    fn to_ref(&self) -> VecZnx<&[u8]> {
+        VecZnx {
+            data: self.data.as_slice(),
+            n: self.n,
+            cols: self.cols,
+            size: self.size,
+        }
+    }
+}
+
+impl VecZnxToMut for VecZnx<&mut [u8]> {
+    fn to_mut(&mut self) -> VecZnx<&mut [u8]> {
+        VecZnx {
+            data: self.data,
+            n: self.n,
+            cols: self.cols,
+            size: self.size,
+        }
+    }
+}
+
+impl VecZnxToRef for VecZnx<&mut [u8]> {
+    fn to_ref(&self) -> VecZnx<&[u8]> {
+        VecZnx {
+            data: self.data,
+            n: self.n,
+            cols: self.cols,
+            size: self.size,
+        }
+    }
+}
+
+impl VecZnxToRef for VecZnx<&[u8]> {
+    fn to_ref(&self) -> VecZnx<&[u8]> {
+        VecZnx {
+            data: self.data,
+            n: self.n,
+            cols: self.cols,
+            size: self.size,
+        }
+    }
+}